Updated May 2015 by Lisa Eitel || Faster controls, easier integration, lower drive prices and the Ethernet have all helped electric actuators, also known as electric linear drives, move into new applications.
“Except for better efficiency,” noted Ernst Blumer, director, Worldwide Sales & Marketing, LinMot, “the performance of electric actuators has not undergone big changes or improvements in the last few years. The variety of actuators, however, has increased. Because of this greater range of actuators, you’ll find them being used in more applications.” More after the jump.
Concurrently, the prices for drives for electric actuators have come down, which has also opened many possibilities for new applications.
“Component costs for electric actuators used in industrial and manufacturing applications are cheaper than ever before,” said Aaron Dietrich, director of marketing, Tolomatic Inc. These components include screws, bearings, motors, cabling and drives. “This trend helps electric actuator technology fit into more and new applications where alternative technologies—such as pneumatic, manual and hydraulic—were typically deployed.”
In many applications, servomotors are replacing induction motors because of their performance and energy efficiency. Direct drives are replacing traditional motor-gearbox combinations because of their high dynamic performance, high precision and long life. And electric actuators are replacing pneumatic cylinders in many applications for similar reasons.
But the biggest improvements in the last five to ten years can be found in the control systems integrated with electric actuators, noted Blumer. Faster bus systems, like industrial Ethernet and real-time communication, make the use of electric actuators simpler.
Servo systems require fast communication and exchange of real-time data between the drive and the overlaid machine control. The bus was always the bottleneck in these systems. Now with the much higher data rates and real-time capacity of industrial Ethernet, the integration and the use of electric actuators is easier.
Keeping it clean
Requirements for hygiene in food and beverage applications have grown. Part of the reason behind this requirement is due to the reduced use of sugar. First, consumers are reducing their consumption of sugary foods. Second, sugar has often been used as a conservation additive. Thus, the less sugar used in food means an increased risk of bacteria and other potential health hazards. Therefore, new machines that fill or pack reduced sugar products need to meet higher demands for hygiene and they need to handle more frequent cleanings. Plus, food and beverage applications are using cleaning agents with higher chemical concentrations and using higher water temperatures during cleaning.
To meet these needs, manufacturers of electric actuators have begun offering stainless-steel actuators with hygienic design and high protection rates up to IP69K. “Electric actuators are available in 300 stainless steel with round bodies, welded joints and other configurations that meet USDA requirements and IP67 and IP69k ratings for caustic washdown and other environments. This is ideal for the meat, poultry and dairy processing markets,” said Dietrich.
Actuators to satisfy specific industry regulations
Another trend in actuators is the requirement to meet new regulations and traceability needs.
Traceability has become an important feature for customers. Of course, quality control is still important too. With just-in-time production, production lot quantities are smaller and product changes on machines and production lines more frequent.
With newer functions and more flexibility, electric actuators help you design adaptable machines with short product change times. Using programmable electric actuators, different movements for different products may be stored in the machine control.
Reducing manual changes in the machine cuts setup time and material waste during setup, as all movements and production data for the new product are defined and stored in the machine control. Also further changes and improvements for each product are automatically stored and documented in the machine control and will guarantee that a product will be produced with the same quality as in the last production lot.
Electric linear actuators are an alternative to pneumatic cylinders in several applications because of the flexibility they deliver in the design of production processes and production monitoring systems. In conveying applications, for example, diverting and sorting functions are more frequently controlled using electric actuators. Typically, pneumatic actuators have been used, but the required manual adjustments were often subject to human error. Plus, the pneumatic actuators could only handle a small amount of variability in product sizes. Electric actuators are flexible by design.
In today’s material handling applications, volume has increased, especially in package size and variability. Electric actuators easily handle these variability requirements and, over the life of the motion system, can be less expensive. In packaging machines, consumer-product manufacturers are producing more package sizes with the same manufacturing lines, which require equipment to be adaptable enough to handle different product sizes and types.
For linear motions in many applications, the efficient electric linear motor in tubular form is a good substitute for many pneumatic components, especially if you compare the total cost of ownership and service.
One of the newer variations of linear electric actuators is the linear-rotary motor from LinMot. The design of this linear actuator combines a linear motor with a servomotor in one unit. The linear-rotary motors can perform any desired combination of linear and rotary motions, and the linear force and the torque can be controlled independently of each other.
For example, this type of actuator easily handles complex tasks such as threading, closing, pick and place, stacking, or aligning where you need linear-rotary motion. In a PET bottle closing machine, the closure cap on the cover must be placed on the bottle using a linear motion along the longitudinal axis, and then screwed onto the threads of the bottle opening with an additional rotary motion until a defined angle or a certain torque has been reached.